JMO, but I think you should add cleaners first. Whenever you add livestock you affect your levels. By adding a clean up crew first you avoid any large losses in case something is wrong or goes wrong. Obviously I am bias about a surface skimmer, but I think you need one. Even a cassette tape, just to eliminate surface scum. A protein skimmer is another thing all together. Some people swear by them. Personally I don't have one at the moment, but will be adding one when I get a chance.
As far as removing the bio balls I think you should. LR rubble in the rear chambers is enough filtration as long as maintain good water quality.
Bob